W. J. McDonald

Thin scintillating tiles with high light yield for the OPAL endcaps

Arrays of thin scintillating tiles with embedded wavelength shifting fibre readout have been installed in the OPAL endcaps to improve trigger performance, time resolution and hermeticity for experiments at LEP II. The arrays were required to have high single-particle detection eƒciency, uniform response, low noise and good time resolution. Limited space for the detector, and a strong magnetic field in the endcap region, resulted in a need for high light output per unit thickness of scintillator, and remote readout. In addition, because of limited space for readout cables, a high light yield per embedded fibre was required. This paper describes the design and construction of a tile array that satisfies these requirements. A light yield of 14 photoelectrons per minimum ionizing particle and a time resolution of 3 ns were obtained during 1997 LEP operation. ( 1998 Elsevier Science B.V. All rights reserved. PACS: 01.52.#r; 29.; 29.40.Mc

Complete Set of Deuteron Analyzing Powers in Deuteron-Proton Elastic Scattering: Measurement and Realistic Potential Predictions

Tensor analyzing powersiT11,T20,T21 andT22, have been measured for deuteron laboratory energiesElabd=75, 85, 95, 106, 119, 131, 144, 156, 172, and 187 MeV. The data are compared to rigorous Faddeev calculations with realistic nucleon-nucleon potentials. A generally good description of the data at all energies is obtained.

The design and calibration of the AHEAD deuteron polarimeter for 120 < Ed < 250 MeV

A new type of deuteron polarimeter to work in the energy range 120 < Ed < 250 MeV has been designed, constructed, and calibrated. The figure of merit (√ϵTkq) has been determined for various polarization components from the calibration data.

The ALTA global positioning satellite based timing system

Abstract The Alberta Large-area Time-coincidence Array (ALTA) experiment uses a number of scintillation detector systems to form a sparse very large area cosmic air-shower detection array. An important scientific goal of the ALTA collaboration is to search for coincidences in the ALTA array due to large area cosmic ray phenomena. A local cosmic ray event, determined by a coincidence of the triplet of cosmic ray detectors forming a local detector system, is time stamped with a temporal coordinate obtained from a GPS receiver. The readout of the data, the local coincidence and the GPS time stamp are all performed in the local readout crate. This time stamp, along with the local shower direction is used to search for coincidences within the large area array. Using two GPS receivers and duplicate sets of ALTA electronics the timing resolution of the GPS time difference between sites was estimated to be 16 ns .

The Saskatchewan-Alberta large acceptance detector for photonuclear physics

Abstract The Saskatchewan-Alberta Large Acceptance Detector (SALAD) is a 4 π detector designed and built for studies of photonuclear reactions with a tagged photon beam. The design and performance of the detector are described. Its characteristics have been studied by examining p-p elastic scattering with a proton beam at TRIUMF.

Quasi‐elastic scattering of polarised protons at 300 MeV

Earlier measurements of the /sup 40/Ca(p vector,2p) reaction at 200 MeV incident energy have been extended to 300 MeV using the TRIUMF polarized proton beam. The angles and energies of both outgoing protons were measured, one being detected in a magnetic spectrometer and the other in a NaI(T) scintillation crystal. Measurements were made in two geometries, in one of which the angles of the outgoing protons were close to equality and the other in which they were very unequal. Values of cross section and analyzing powers for the knockout of protons for ld/sub 3/2/, 2s/sub 1/2/, ad ld/sub 5/2/ shells in /sup 40/Ca were obtained and are compared to DWIA calculations incorporating spin orbit terms in the optical potentials, and also to calculations using optical potentials derived from a relativistic approach based on the Dirac equation. 1 reference.

Elastic scattering of polarized protons at 200 to 500 MeV

We have measured proton elastic scattering cross sections and analyzing power angular distributions on Ca and 208Pb at 200, 300, 400, and 500 MeV. The 400 MeV data from 208Pb have been fitted by an optical model and also compared with results of Impulse Approximation calculations.

Quasi free scattering of polarized protons from 40Ca

Measurements have been made of the cross section and asymmetry of the 40Ca(p↘,2p) reaction. Peaks corresponding to the knockout of protons from the 1d3/2, 1d5/2 and 2s1/2 shells are seen. By comparing the asymmetry for protons from the 2s1/2 shell with that arising from free p‐p scattering, information on spin orbit distortion effects is obtained.This experiment was performed using a 200 MeV polarized proton beam from the TRIUMF cyclotron. The polarization and interacting of the incident beam were monitored in a polarimeter and an ion chamber. The energies and angles of outgoing protons were measured by four detector telescopes consisting of plastic scintillation counters, multi‐wire proportional chambers, and 75 mm thick × 125 mm diameter NaI (Tl) scintillation crystals. Coincidences between particles traversing detector telescopes on opposite sides of the beam line were recorded. Missing energy spectra for events with recoil momenta ∠ 0 MeV/c and ∠ 100 MeV/c are shown in Figures I(a) and I(b) respective...

Reaction mechanisms in {sup 12}C({gamma},{ital pp}) near 200 MeV

Inclusive {sup 12}C({gamma},{ital pp}) cross sections have been measured with tagged photons in the range {ital E}{sub {gamma}}=187{endash}227 MeV using the Saskatchewan-Alberta Large Acceptance Detector (SALAD). The large angular acceptance allowed the measurement of noncoplanar {ital pp} emission. The cross sections were compared to a Monte Carlo intranuclear cascade calculation. Agreement was reasonable for the shapes of the cross sections but the calculated total cross section was 3.9 times larger than the data. {copyright} {ital 1996 The American Physical Society.}

A Knockout Reaction Study with a Polarized Proton Beam

The knockout reaction 16O(p⇀2p) has been studied with a polarized beam at 200 MeV. Strong j‐dependence of cross section is observed, indicating that under appropriate kinematic conditions knockout protons may be polarized.